Log more sensibly when we can't get sha256
Log more sensibly when we can't get sha256

Issue #7550

justinsb/kops,robinpercy/kops,justinsb/kops,kubernetes/kops,aledbf/kops,aledbf/kops,aledbf/kops,robinpercy/kops,kubernetes/kops,justinsb/kops,kubernetes/kops,robinpercy/kops,aledbf/kops,robinpercy/kops